Inspection of various piping systems and pipelines for defects, cracks, corrosion, wear and the like is important for maintaining the integrity of such systems, and avoiding potentially catastrophic consequences from failure of pipes during use. In some applications the piping systems are used to transport hot and/or corrosive materials. Often such piping systems are provided with an exterior layer of insulation or the like, which prevents visual inspection of the piping system, and inhibits conventional inspection systems that require direct access to the pipes. In another example, piping systems for transporting petroleum products or the like over large distances often include a thick layer of polymeric insulation and an outer metal sheathing. Such piping systems are extremely difficult and costly to effectively monitor for wear, corrosion, damage and similar defects. Other piping systems are difficult to access for other reasons. For example, piping systems and risers associated with off-shore drilling, including for example steel catenary risers, are substantially located underwater, and therefore difficult and expensive to monitor. Such piping systems may also be coated or encased with a protective outer casing, for example a plastic or elastomeric outer jacket.
Non-invasive analysis of pipes can be performed by inspecting eddy currents induced in a section of the pipe. However, existing methods for processing and analyzing eddy currents are either too slow or suffer from poor signal-to-noise ratios. Accordingly, there is a need for improved eddy current inspection techniques.